Research goals for work in progress: 1. To determine by electron microscopy the intracellular location of hexokinases P-I and P-II in the yeast cell. 2. To elucidate the factors controlling synthesis of hexokinase P-I. 3. To determine the requirements in terms of size and charge for the stimulatory effect of precipitates on sugar uptake by cultured fibroblasts. 4. To ascertain whether the adenosine effect (suppression of sugar uptake by cultured fibroblasts) is due to increased formation of elements of the sugar transport system.